Sunday, November 30, 2014

Once again, Sure Electronics modified their 32x16 3mm LED display, and this time not only cosmetically.
The two 16-pin shrouded male connectors have been replaced with 10-pin connectors. And the worst thing is that the display now requires 12V for power! Maybe these new displays are intended for use in vehicles powered by 12V batteries. Or maybe designers thought a 12V power source is easier to access than a 5V one. In any case, the display has an on-board DC-DC switching regulator (with XL4013) to make the required 5V.

For someone who needs to replace the older model with the new one, the immediate consequences are:

the connector between the driver board (e.g. Wise Clock 4) and the display won't work; connections must be re-wired, probably using an adapter cable;

either supply 12V to the board through the connector, or hack the display by soldering the 5V wire directly to the board (see the photos);

the holes won't align anymore.

The good news is that the display is electrically compatible with the old one. With the correct re-wiring, the display should work without any software changes.

The following photo shows the testing of the display with the Wise Clock 4 board (and it works just fine).

The display has a series of rail bars that can be used for soldering the 5V power wire, as shown below.

A new design based on this display should (or must) use a 12V power supply. Powering from the USB is not an option any more. This would require a re-design of the Wise Clock 4 board as well (USB connector would be useless now; the FTDI cable won't be able to power the display).

Saturday, November 29, 2014

I have the bubble LED shield working with the DS1337 RTC & LiPo shield.
I have it alternating the display with the battery voltage every 2 seconds
right now. I don't have a voltmeter handy, so I haven't verified what is
displayed with actual voltage. It started fully charged at 4.2v and has now
dropped to 4.1v. It should start blinking at 3.45v, and go to sleep at
3.3v.I started with your original bubble sketch from the blog posting, but then
had to remap all the display pins from the schematic. The current version of
the SevenSeg library doesn't match your code, so I had to make some
adjustments.I also changed the SevenSeg library code to even out the brightness. It
looped through all the segments and turned on each appropriate digit, then
delayed and turned everything off.I changed it to loop through all the digits, turning on each appropriate
segment. Once all the appropriate segments are lit, it turns on the current
digit, delays, then turns everything off, then moves to the next digit. With
the previous method some segments were bright and some dim, depending on what
was displayed on the other digits.I also changed the SevenSeg library to not blank leading digits. It now
displays 01.36 for 1:36 AM. I left it as a 24-hour clock. I can only display a
decimal point, not a colon.

Thanks again Mike!

From ScottH, another version (HDSP.ino only; the rest of the files are unchanged) of the HDSP clock sketch adds scrolling of the time and date and improved setting. Thanks Scott!

Here are the pictures. Hope you find it interesting, unique
at least. There is a slide switch in the back with selections Solar charge,
USB charge, USB run (the default mode of the kit), and battery run where you
press that button on the front to turn on and display the time. I used a
solar/USB charge board from Adafruit as I am no EE to figure out how to charge
a battery from solar and USB with all of the correct regulated voltages etc.
The case is made from corian and in the top view those speckles are a kind of
metallic flake in the corian, the center band is pure black.

We got the package last week and my 13 yr-old grandson and I soldered it
together and powered it up. Works perfectly!! Then I got your Arduino code for
it and programmed it with a flashing ':' between hours and minutes and between
minutes and seconds. Then I set the date in the RTC and changed the code again.
Now it shows the date for 2 seconds every minute. Nice! Thanks for a great
project!

Your kit is fantastic. Simple but well thought out. Thanks for bringing it to
the market!I would like to use it in one of my classes
at Stanford as an "intro to soldering" and "intro to Arduino hacking" (they
already will be familiar with the Uno) project.

Thank you Florin for the very thoughtful and
entertaining gift. Anything based on
electronics is always interesting to me. We have been reading the famous quotes
all day. It was a pleasure to meet you [...]

I could have added a second bubble LED display to my "bubble clock" by connecting the anodes for the 4 new 7-segment digits to the only 4 pins left available: D0, D1, A6 and A7.
Instead, I preferred to use the expensive ($8+) LED driver MAX7219. Luckily, I got mine a long time ago as free sample from Maxim, and this was my chance to use it. As one can expect, the "double bubble" clock can display the seconds, plus the date and day of the week.

Below are the 2 bubble clock versions side by side. Both are ProMini shields, so ProMinis get plugged on their backs. I designed them to stand by themselves with the electronics exposed and on the open, as shown in this post. I am not sure if this is a good idea, but designing (or finding) an enclosure seems even a bigger challenge.

The sketch, included below, uses the LedControl library (communicates with MAX7219 through SPI).